London breaking dawn premiere!

Hi there, im a 12 going onto 13 year old girl from scotland, the closest place for me to go to any of the twilight premieres is in london, i am a massive twifan, and im in love with the cullens! especially edward! i have never been to anything like this before, so im not exactly sure on where to get tickets from and booking hotels etc, could anyone please help me, oh and roughly on the cost also! thank you , love holly <3 xx